Brainlag PlusVoltage from two metals of different reactivity, batteries, rechargeable cells, and the hydrogen fuel cell.
Two metals, one voltage
Two different metals in an electrolyte make a cell.
The more reactive metal is the negative electrode. The bigger the difference in reactivity, the bigger the voltage.
- magnesium against copper: 2.7 V; zinc against copper: 1.1 V
- magnesium against zinc: 2.7 − 1.1 = 1.6 V
A battery is two or more cells in series: the voltages add. A non-rechargeable cell stops when a reactant is used up; a rechargeable one is reversed by an external current.
The rest of this lesson and its 11 practice questions are in Plus.
Screen 1 of 2, free to read.
- 11 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards